Texture problem with Makehuman model in blender
UV map is a coordinate system that helps to wrap a 2D image around your 3D object.
You can read a little about UV's here http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro/UV_Map_Basics

Here is your situation.



What you see in white is your texture, exported from Make Human. The wires you see are your UV map. To look good they must match. I don't know how you ended up with sweeter when your character in Make Human had T-shirt, but I think this is your problem.

To fix it you need 1 of 2. Either edit your UV's to match the texture or edit your texture to match the UV's. You can read about the first way in the link I gave you, and you can edit the 2nd in any image editing software.